Machiavelli: The $80 million (or $105 million that SC cites) attributed to Capone was a gross figure, and most biographers (like John Kobler) note that nearly all of it went out for payoffs to the cops, politicians, lawyers, etc. Plus, Capone was a degenerate gambler who thought nothing of betting half a mil on a single horse race. The fact that he didn't pay income tax is a combination of greed and stupidity: Kobler notes that the gov't gave him a chance to settle up and he passed it by.
Annt: Lepke Buchalter formed Murder Inc. as an enforcement arm for his rackets. Conglomerator that he was, he soon got the idea of allowing Murder Inc. to do contracted hits for others, turning it into yet another "profit center." Supposedly they did about 1k hits. As you'd expect, this volume vastly exposed their vulnerability to the cops, who put the squeeze on two top Murder Inc. killers: Abraham (Kid Twist) Reles and Allie (Tick Tock) Tannenbaum (who got his name because if Allie was after you, the clock was ticking on your life). They squealed, particularly Reles. Lepke took it on the lam for two years, during which time he had several witnesses against him killed. He finally surrendered to the Feds, thinking he'd go away for a narcotics rap. The feds turned him over to NY State, which prosecuted him for murder and sent him to the chair.
FH: Though Lansky was reputed to have been worth $300 million, his biographer, Robert Lacey, notes that the figure was erroniously stated by a journalist, Hank Greenspun, who subsequently admitted the mistake. Lacey believes Lansky was worth, at his peak, $5 million--not chopped liver, but not $300M, either. He died more or less broke, after using his last $50k for an operation on his neer-do-well son, Buddy. Lacey says the reason Lansky died peacefully at age 81 was that he was never rich enough or powerful enough to attract jealousy from other Mob bosses: "He was the accountant, not the boss."